CLINICAL PRACTICE Exercises in Clinical Reasoning Doing What Comes Naturally Mark C. Henderson, MD1, Gurpreet Dhaliwal, MD2, Stephen R. Jones, MD3, Charles Culbertson, DO3, and Judith L. Bowen, MD1 1Department of Internal Medicine, UC Davis Medical Center, Sacramento, CA, USA; 2Department of Medicine, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA; 3Department of Internal Medicine, Legacy Health System and Oregon Health and Sciences University, Portland, OR, USA. KEY WORDS: diagnostic reasoning; secondary hypertension; problem representation; illness scripts; clinical problem solving. J Gen Intern Med 25(1):84–7 DOI: 10.1007/s11606-009-1187-2 © Society of General Internal Medicine 2009 In this series, a clinician extemporaneously discusses the diagnostic approach (regular text) to sequentially presented clinical information (bold). Additional commentary on the diagnostic reasoningprocess (italic) is interspersed throughout the discussion. A 59-year-old man presented to the emergency depart- ment with palpitations, weakness, and faintness. Palpitations are typically benign unless there is evidence of decreased cardiac output or decreased cerebral perfusion, e.g., syncope or presyncope. Because of the associated presyncope, a cardiac etiology becomes much more likely and requires a thorough search for arrhythmia or occult cardiomyopathy. In the preceding week he had experienced several episodes of palpitations without associated symptoms. Weakness and faintness developed that morning. He had no chest discomfort or loss of consciousness. He denied fever or chills. He had been seen regularly by his personal physician for routine health maintenance. Systolic hyper- tension had been diagnosed 18 months earlier. Treatment with verapamil (240 mg per day) was initiated 13 months ago. Olmesartan (40 mg per day) was added 9 months ago. Hydrochlorthiazide (12.5 mg per day) was added 1 month prior to presentation.